1. Field of the Invention
The present invention relates to a knee brace, and more specifically relates to a knee brace incorporating at least one locking hinge having a free floating center of rotation.
2. Prior Art
Braces are often utilized to support the knee when damage, deformation, surgery, or the like has caused the knee to be instable. Most often, a knee brace is used to protect the knee against further injury and/or to provide extra support for a previously injured knee during periods of activity such as when the user walks, runs or participates in athletic events.
Prior art knee braces have taken a variety of different forms and complexities. Knee braces have in the past been as simple as a wrapping of materials such as an elasticized band around the knee joint. Such wrappings, although causing a loss of mobility, nevertheless strengthen the joint to some degree. Complex and/or rigid knee braces, including casts or other completely immobilizing devices have also been used in the past. In between these extremes, there are numerous devices which are attached to the upper and lower leg and include hingeable members located at the knee joint. These types of braces are intended to provide some sort of support for the knee while attempting to preserve maximum mobility.
It has been known in knee braces of the last mentioned type to include structural features in the hinging portions thereof which prevent the knee joint from being hyperextended. Further, it is known in this type of prior art brace to include structural elements which cause the rotational motion of the hinge to somewhat imitate the hinging motion of the knee joint itself.
Knee braces incorporating the above-mentioned concepts are exemplified by the U.S. Pat. No. 4,791,916 to Paez. Paez discloses a knee brace having upper and lower cuffs which are attached respectively to the upper and lower portions of the leg above and below the knee. The cuffs are attached so as to orient a pair of polycentric hinges adjacent the medial and lateral sides of the knee in order to control the extent of leg flexion and extension.
It has in the past been very difficult to incorporate a polycentric type hinge into a knee brace which is also capable of preventing hyperextension of the knee. This is because the design necessary to track the hinging motion of the knee joint becomes complicated with the incorporation therein of a locking mechanism. This has been because the structural elements necessary to cause the hinge to lock in a predetermined position to prevent further hinging motion, tends to interfere with the rotational capabilities of the hinge.
Prior art devices which attempt to incorporate a locking mechanism into a polycentric type hinge for limiting the hinge's pivoting motion to prevent hyperextension of the patients knee, have in the past had an added problem of maintaining desired positioning on the user's leg. This is because these types of knee braces tend to slide upward or downward on the user's thigh during motion of the knee due to ineffectiveness of the brace in duplicating the leg's hinging motion. Forces generated by the engagement of a locking mechanism in the brace's hinge also tend to cause slippage of the brace. Brace slippage upward or downward on the user's leg, causes the brace's hinges to move from their correct position at the sides of the knee, which in turn causes the brace to misfunction. Sometimes this slippage, if extensive, can even render the brace hazardous to the patient.